Process of drying air and apparatus intended therefor

ABSTRACT

In a process of conditioning air in a multi-channel system comprising a first group of channels passed by a cooling agent and a second group of channels disposed alternately therebetween and passed by the air to be conditioned and having its walls coated with a sorbing agent, the cooling agent removing the heat set free by absorption of moisture from the air to be conditioned by heat convection through the walls between the groups of channels, the cooling is to an essential degree effected by evaporation of water into the cooling agent passing through the channels of the first group of channels. Preferably, the process includes also a particular mode of regeneration of the sorbing agent by a heating fluid supplied intermittently to the channels of the first group and accumulated by the walls of said channels covered with a wettable or water absorbent material. The apparatus for carrying out a process of air conditioning according to the invention comprises an exchanger body housed in a casing and formed with two groups of channels, the channels of one group being positioning alternating with the channels of the second group, the channels of the first group being adapted to be passed by a cooling agent admitted through an inlet and discharged through an outlet in the casing, and the channels of the second group being adapted to be passed by the air to be conditioned admitted through an inlet and discharged through an outlet in the casing. The walls of the channels to be passed by the air to be conditioned are provided with a coating of a hygroscopic substance acting as a sorbing agent, whereas the walls of the channels for the cooling agent by a coating of a sorbing agent are made adapted to be wetted taking up water which is evaporated into the cooling agent when it passes through said channels. Preferably, all or part of the water is supplied intermittently as a heating agent for regeneration of the sorbing agent.

United States Patent Glav [ 1 PROCESS OF DRYING AIR AND APPARATUSINTENDED THEREFOR [72] lnventor: Ola Glav, Vallentuna, Sweden [73]Assignee: Carl Georg Munters, Stocksund,

Sweden [22] Filed: July 6, 1970 [21] Appl. No.: 52,184

[30] Foreign Application Priority Data July 17, 1969 Sweden ..l0ll3/69521' vs. Cl. ..Q ..55/34, 55/61, 55/390 [51] Int. Cl. ..B0ld 53/06 [58]Field of Search ..55/33, 34, 32, 61, 62, 208, 55/390 [56] ReferencesCited UNlTED STATES PATENTS 3,528,224 9/1970 Warn ..55/208 3,446,0315/1969 Chi et al. ..55/34 3,251,402 5/1966 Glav ..55/34 2,687,783 8/l954Watkins ..55/61 2,993,563 7/1961 Munters et a] ..55/34 3,498,026 3/1970Messinger et a1 ..55/390 In a process of conditioning air in amulti-channel system comprising a first group of channels passed by [1513,683,591 [55] Aug. 15,197;

a cooling, agent and a second group of channels disposed alternatelytherebetween and passed by the air to be conditioned and having itswalls coated with a sorbing agent, the cooling agent removing the heatset free by absorption of moisture from the air to be conditioned byheat convection through the walls between the groups of channels, thecooling is to an essential degree effected by evaporation of water intothe cooling agent passing through the channels of the first group ofchannels. Preferably, the process includes also a particular mode ofregeneration of the sorbing agent by a heating fluid suppliedintermittently to the channels of the first group and accumulated by thewalls of said channels covered with a wettable or water absorbentmaterial. The apparatus for carrying out a process of air conditioningaccording to the invention comprises an exchanger body housed in acasing and formed with two groups of channels, the channels of one groupbeing positioning alternating with the channels of the second group, thechannels of the first group being adapted to be passed by a coolingagent admitted through an inlet and discharged through an outlet in thecasing, and the channels of the second group being adapted to be passedby the air to be conditioned admitted through an inlet and dischargedthrough an outlet in the casing. The walls of the channels to be passedby the air to be conditioned are provided with a coating of ahygroscopic substance acting as a sorbing agent, whereas the walls ofthe channels for the cooling agent by a coating of a sorbing agent aremade adapted to be wetted taking up water which is evaporated into thecooling agent when it passes through said channels. Pregerably, all

or part of the water is supplied intermittently as a heating agent forregeneration of the sorbing agent.

25 Claims, 11 Drawing Figures 2 w a i! 6 5 m m mm a a lNVENTO/E A 7"TO/PNFV SHEET 0 1 OF OLA GLAV XJQJLU PATENTEBAU: f5 1912 PA TENTEU3.683.591 sum DEUF 10 lNVE/VTOR OLA GLA V A TTORNEY PATENTEDAUB 15 1mSHEET 0 3 BF INVEN TOR /r@ BMW ATTORNE Y PATENTED M18 15 1912 SHEET 050F lNVE N TOR.

PATENTEDMJQ 15 I972 SHEET 08 0F Fig.6

/ N VEN TOR.

OLA GLAV AT'I'ORNEY PATENTED AUG 1 s 4972 SHEET 07 0F IN VENTOR OLA GLAVPATENTEBAUE 1 5 1912 SHEET 08 0F INVENTOR OLA GLAV ATTORNEY PATENTEDAus15 I972 SHEET 100F 10 IN VE N TOR.

OLA GLAI/ By ATTORJVE) BACKGROUND OF THE INVENTION The present inventionrelates to a method of drying air in a multi-channel system having afirst group of channels through which are passed a cooling agent, and asecond group of channels alternately disposed between said channels andthrough which is passed the air to be conditioned and dried, the wallsof the channels constituting carriers for a sorbing agent or sorber. Thecooling agent by heat conduction or convection through the walls of thechannel removes heat set free by the absorption of moisture from the airto be conditioned. The cooling agent thus has for its purpose theremoval of condensation heat produced by the moisture of the air to beconditioned being taken up by the sorber or drying agent, whereby theair to be conditioned can be dried to predetermined absolute humiditywithout necessitating the relative humidity of the air at the same timeto be lowered to extremely low values.

THE PRIOR ART It has been suggested to use as cooling agent air such asatmospheric air which can take up a quantity of heat with correspondingincrease of temperature. Over this prior art the invention issubstantially characterized by the feature that the cooling to anessential degree is effected by evaporation of water into the coolingagent within the channels of said first group. In prior art practice thedrying agent must be regenerated at certain intervals by removal of theabsorbed water by means of a heating agent. According to anotherimportant feature of the invention the walls of the channels of thefirst group are caused to accumulate water, which is intermittentlysuppliedby the heating fluid flowing through said channels.

By thus effecting the removal of heat from the hygroscopic drying agentaccording to the invention essentially by evaporation of water from thewalls of the channels of the first group, the cooling capacity of theconditioning apparatus becomes considerably greater than when only theown sensible heat content of the cooling air would be made use of.According to the invention many advantages are obtained, because due tothe substantially increased cooling capacity of the cooling air per unitof volume the quantity of cooling air can be reduced and the channelscan be made minor for one and the same effect, which in an advantageousmanner influences the economy of operation. In addition, the evaporationof water into the cooling air results in that lower temperatures areattained and thereby a deeper drying of the air to be conditioned isobtained. The quantity of heat which is removed from the air to beconditioned, according to the invention, can even be so great that thetemperature of the conditioned air will be lower after the drying thanbefore said (1 'ng.

ficcording to still a valuable property of the invention the heattransfer between the two groups of channels is solely effected byconvection in the wall material which for this purpose is essentiallyimpermeable to both vapor and sorbing agent.

THE DRAWINGS Further objects and advantages of the invention willbecomeapparent from the following description, considered in connectionwith the accompanying drawings, which form part of this specification,and of which:

FIG. 1 is a perspective view of a drying apparatus constructed forcarrying out the process of the invention.

FIG. 2 is an illustration of the principal structure of the variousgroups of channels in the embodiment according to FIG. 1.

FIG. 3 is a diagrammatic illustration in a larger scale I of portions ofchannels forming a part of the same embodiment.

FIG. 4 is a perspective view of a portion of the exchanger body withassociated co-operating members for regeneration of the sorbing agent.

FIG. 5 is a perspective view of another embodiment for carrying out theprocess of the invention.

FIG. 6 is a perspective view of the exchanger body used in theembodiment according to FIG. 5.

FIGS. 7 to 9 are perspective views of three various embodiments of anexchanger body formed with channel systems.

FIG. 10 shows a conditioning plant comprising a drying apparatus of thetype shown in FIG. 5.

FIG. 11 is a graph. I

In the various embodiments of the invention the same or equivalent partshave in many cases been give the same reference numerals.

DETAHJED DESCRIPTION OF APPARATUS ACCORDING TO THE INVENTION Referringnow to the drawings and in particular the embodiment illustrated inFIGS. 1, 5 and 10 reference numeral 10 denotes a casing which houses anexchanger body 12 formed with channel systems. Said exchanger body isformed to be operated according to the counter-current principle withrespect to the two fluids passing through said body. The air to bedried, thus the air to be conditioned, is introduced through a tubesocket 14 mounted on the rear side of the casing 10 according to FIG. 1adjacent the lower portion of the exchanger body 12. The dried andconditioned air escapes through a tube socket 16 at the opposite side ofthe apparatus and at the upper part thereof. Cooling air which may beconstituted by consumed conditioned air is supplied to the apparatus atthe top through an opening in the casing 10 and escapes into the outerat mosphere through a lateral socket 20 located at the lower part ofsaid casing as shown in FIGS. 1 and 5.

As is especially evident from FIG. 2, the body 12 is in the embodimentnow in consideration subdivided by partitions generally denoted as 22,into two groups of interspaces or channels of which the one is passed bythe cooling air and the other by the air to be conditioned. Theinterspaces 23 for the cooling air are open at the top and at the bottombut laterally closed by covering frame elements 26. Further theinterspaces between the two parallel walls 22 are subdivided into branchchannels 24 by means of partition walls 28. Alternating channels orinterspaces for the air to be conditioned are positioned between thechannels 23, said interspaces in the embodiment according to the FIGS.

l 4 also being subdivided into branch channels 30 which substantiallyhave the form of a Z. Straight opposite the inlet socket 14 the channels30 are formed with openings 32 directed towards said socket and aretherefrom passed out over the entire breadth of the exchanger body 12 bymeans of partition walls 34. The channels then extend upwards towardsoutlets 36 located straight opposite the escape socket 16. The air to beconditioned streaming through the channels 30 is thus given along themajor part of the walls 22 of the body 12 a vertical upwardly directedflow whereas it at the ends of the channels for shorter distances flowshorizontally. The two air streams thus pass one another substantially incountercurrent. Except for the inlets 32 and the outlets 36 the channels30 are closed by means of frame members as is indicated at 38, 39, 40,41 in FIG. 2.

The partition walls 22 are composed of three layers as in an exaggeratedscale is shown in FIG. 3. Of these layers a thin intermediate layer 42is of a material which is difiiculty permeable or nonpermeable to waterin liquid or vapor state, which property is owned by certain plasticsubstances. This intermediate layer is coated on that side which facesthe cooling air channels 24, with a layer 44 of a wettable or waterabsorbent or water retaining material, such as paper of cellulose orasbestos fibers. The channels 30 for the air to be conditioned locatedon the opposite side of the intermediate layer 42, have on their wallscoatings of a hygroscopic or moisture absorbing substance, such aslithium chloride. Secured on the intermediate layers 42 can be carriers46 of thin porous or fibrous material which is impregnated with themoisture absorbing substance.

Water is supplied to a circulation system in the apparatus from a pipe48 suitably connected to a main and provided with a valve 49 (FIG. 1).This system comprises a riser 50 in which a heater 52 is provided andwhich at the top opens into a hose 54 which in turn is connected to oneor several spraying devices 56 (FIG. 4) with bottom outlet holes abovethe channels 24. The supplied hot water flows downwards through thesechannels to be collected in a trough 58 between which and an inlet pipeto a pump 62 driven by a motor 61, a tube 64 is provided. The deliveryside of the pump 62 is in connection with the riser 50. Through thecirculation system described and the vertical channels 24 for thecooling air a circulation of water which is heated in the heater 62 upto almost the boiling point, is effected, as will be described in moredetail in the following. Some supply of fresh water in addition to thequantity of water evaporating in the channels 24 can be brought aboute.g. by forming the trough 58 with an overflow 66 through which watercan flow down to the lower part of the apparatus which has a drain 68.In this manner the water circulating in the system is prevented fromaccumulating salts and the like (minerals) in undesirable degree whichcould be deposited on the porous layers 44.

The spraying device 56 at its top and its sides is encased by a hood orcap 70 having lateral flanges 71 of such shape as to cover one inletlayer at a time so that cooling air is prevented from passingsimultaneously with the heating agent or fluid, i.e. the hot water,through the channels 24 and to cool the channels 30 which are beingregenerated at that moment. The hood together with the spraying device56 is actuated by a driving mechanism such as a screw 72 so as slowly tomove in one direction over the upper surface of the exchanger body 12whereby the individual rows of channels 24 in succession are sealed offfrom supply of cooling air and instead are contacted with the heatingfluid. The screw 72 is rotated by a motor 73 and a W- belt 74 runningabout pulleys 75, 76, 86. From a pulley 77 on the shaft of the motor 73a belt 78 extends downwards with its end entrained about a drivingpulley 79 for a worm 80 which moves the trough 58 across the apparatusin horizontal direction synchronously with the hood 70. The hoseconnections 54 and 64 accomodate the axial motion of the hood 70 and thetrough 58.

Provided in the outlet socket 16 for the conditioned air is a screen orshield 82 formed with lateral flanges 83 and which is similarly drivensynchronously with the hood 70 by means of a worm 84 which is rotated bythe pulley 86 driven by the belt transmission 74 from the motor 73. Thisscreen has for its object to prevent that air which is present in thechannels 30 in front of, and laterally adjacent the hood 70, fromescaping through the tube socket 16 to the place of utilization of theconditioned air. The screen 82 thus follows the spraying device 56during the horizontal motion thereof and is located in front of theopenings 36 of the one or the two channels 30 adjacent that row ofcooling air channels 24 which for the moment are heated by means of thehot water. The air which in this way is stopped by the screen 82 isdischarged through bellows 88 into the ambient atmosphere. Other rows ofchannels for air to be conditioned are sealed ofi entirely, as explainedbelow in more detail. The bellows can change their lengths in responseto the position of the screen 82. The horizontal motion of the elements70, 82 and 58 can be adjusted so after having passed over all rows ofchannels 24 and 36 they may return with greater speed to the oppositeside of the exchanger body, during which motion the supply of hot watermay be interrupted by means of members (not shown).

OPERATION OF THE DESCRIBED APPARATUS The described apparatus is operatedin the following manner. During operation the air to be conditioned istaken in through the tube socket l4 and flows upwards through thechannels 30 to the outlet socket 16 and from there to the space themoisture content or humidity of which is to be controlled. During thepassage through the channels 30 the air comes in contact with thesorption layer 46 so that moisture present in the air is absorbed bysaid layer. At the same time cooling air passes in downward directionthrough the channels 24 the wall layers 44 of which earlier have beenwetted so that an evaporation into the cooling air is provoked. Whenmoisture is absorbed in the channels 30 by the layers 46, the normalheat of condensation is released. This is conducted through the thinwalls 42 to the released layers 44 in the channels 24. Since the layers44 contain water heat can now be taken up by the cooling air due to theevaporation of the water in the channels 24. In this way an intensiveconvection of heat is obtained so that the temperature of the sorptionagent and of the air to be conditioned and flowing within the channels30 is maintained at a low value this in turn results in that theabsorption of moisture becomes extremely good also when high relativemoisture contents are in consideration. The quantity of cooling airwhich is required may be only a fraction of the quantity which would berequired if only the inherent sensible heat content of the cooling airwere utilized for the cooling. Hence the apparatus attains theadvantages of relatively small dimensions and low costs of operation.

The sorbing agent must be regenerated at regular intervals by expellingthe water taken up earlier. This regeneration is effected by means ofthe circulation system for hot water. Said hot water is supplied insequence to the various rows of channels 24 for the cooling air, thelayers 46 in the adjacent channels 30 for the air to be conditionedbeing heated simultaneously to so high a temperature that the moistureis removed from the drying agent. This moisture is then carried away bythat branch stream of the air to be conditioned which escapes throughthe bellows 88 into the surrounding atmosphere and thus is not admixedto the conditioned air flowing to the place of consumption. The dryingby means of hot water is rendered possible by the partition walls 42difficulty permeable to moisture.

The coatings 44 in the cooling air channels 24 will be wetted when hotwater is flushed therethrough and they will accumulate water which thenis utilized during the drying of the air to be conditioned to removeheat by evaporation of water into the cooling air streaming through thechannels 24.

As will be seen from FIG. 4, the screen 82 has an inner opening of awidth corresponding to the width of two interspaces or channel rows inthe exchanger body 12. The open width of the hood "70 is greater, suchas, e.g. corresponding to four interspaces or channel rows. Therefore,hot water is always supplied simultaneously to two or three rows ofchannels 24 depending on the position of the hood during the advancementthereof. In the case with three channel rows the two outer ones are onlypartially open, but sufficiently to allow hot water to be flushed downinto them. One row of channels 24 will thus always on one or both sidesbe adjacent to a row of channels 30 which is passed by regeneration airwhich escapes through the screen 82 to the outlet 88. At the same timeeach of the flanges 71 of the hood 70 ought to screen off at least oneinterspace width and each of the flanges 83 of the screen 82 at leastthree interspace widths. This is to prevent cooling air from passingthrough a row of channels 24 which is adjacent a row of channels 30which on its op posite side is being heated by hot water flowing throughthe row of channels 24 located there. Further, no air to be conditionedis to be permitted to pass through a row of channels 30 which isadjacent a row of channels 24 the walls of which had not enough time tocool down after having been flushed with hot water.

The dimensions set forth above for the hood 70 and the screen 82 are tobe regarded as minimum dimensions only. Thus, it is advantageous tosupply heating fluid simultaneously to several and most suitably agreater plurality of rows of channels 24 by means of several sprayingdevices 56, a corresponding number of channels for conditioned air atthe same time being subjected to regeneration. The regeneration will,however, in this case also be effected in a minor portion of number ofrows of channels which at one moment are located in front of the twoelements and 82.

STRUCTURE AND OPERATION OF APPARATUS WITH EXCHANGER BODY FOR CROSS-CURRENT OF FLUIDS In the embodiment according to the FIGS. 5 and 6 theexchanger body 12 is formed so that the two fluids pass through the samein cross-current.

All layers of the exchanger body 12 are corrugated, the corrugations ineach second layer forming an angle with the corrugations 92 in theintermediate layers. These angles are at the same time inclinedrelatively to the horizontal and the vertical planes. The interspacesbetween every second pair of layers are closed at the top and bottom bymeans of strings or strips 94 of some suitable tightening material. Onboth sides thereof open channels 24 are formed. However, pairs of layerspositioned therebetween are closed along vertical edge strings or strips96, so that channels 30 for the air to be conditioned are formed.Between the strings 94 and 96, respectively, the individual channelswill extend over the surface of the exchanger body with a width varyingfrom 0 at the places where the layers are in contact with one another,to the double height of the corrugations. The individual layers have thesame composition as those described in connection with FIG. 3.

The air to be conditioned passes through the channels 30 of the body 12in a horizontal main direction according to the arrows 98 towards theoutlet socket 16. The cooling air is introduced through a tubular socket100. The exchanger body 12 is provided with a vertical partition wall102 which divides it into two halves. Therefore, the cooling air flowsupwards from the inlet socket 100 in the right-hand half according toFIG. 5 as is indicated by the arrows 104. Between the upper edge of theexchanger body and the roof of the casing 10 there is an interspace intowhich the cooling air flows over to the left-hand half of the exchangerbody whereunder it is deflected as indicated by the arrows 106, and thenflows downwards to the outlet 20. The cooling air thus passes twicethrough the exchanger body 12 under repeated cross-current flow relativethe horizontal direction of the air to be conditioned.

In the same manner as in the preceding embodiment a hood 70 within whichat least one spraying device 56 is provided, is conveyed to and fro atthe upperside of the exchanger body for intermittent supply of heatfluid in the form of hot water to the cooling air channels 24. At thebottom two troughs 58 are provided for receiving heating fluid from oneand the other half of the exchanger body. These troughs are connected attheir bottoms to flexible hoses 64 for conveying of the heating fluidimpelled by the pump 62 back to the heater 52 and the top face of theexchanger body. 1

In this case the screen 82 has an extension corresponding to the entireheight of the exchanger body 12 so that the channels 30 which areundergoing regeneration of the sorbing agent are entirely sealed off andthe moist and consumed regenerating air instead escapes through aflexible hose 88 into the surrounding atmosphere. In this case thescreen 82 is located at the inlet side for the air to be conditionedwhich thus in the regeneration zone passes in a direction opposite tothat in the other channels 30 as is indicated by the arrow 108. The hood70 and the screen 82 have been illustrated diagrammatically and thusshould in reality have the same structure as described above inconnection with FIG. 4.

The elements 70, 58 and 82 perform synchronized movements in the samemanner as in the preceding embodiment, for which purpose they may bedriven from the common motor 73, the shaft 110 of which drives atransmission 112 for the hood 70 and a transmission 114 for the twocollecting troughs 58. A shaft 117 driven by a pair of conical gears 116transmits the movement of the shaft 110 to a transmission 118 for thescreen 82. The said transmissions can be made with belts l 19 one sideof which is connected with a pin 120 provided on one of the elements, e.g. the screen 82.

Laterally of the exchanger body there may be provided straight guidemember 136 or the like (FIG. 6) in correspondence to the various rows ofchannels 24. Similar straight guide members 138 are provided along oneside in correspondence to the various rows of channels 30. These guideelements have for their purpose to constitute supports and tighteningmeans for the hood 70 and the screen 82, respectively, during themovements thereof.

OTHER EMBODIMENTS OF THE EXCHANGER BODY The embodiment illustrated inFIG. 7 has in the same manner as the preceding embodiment an exchangerbody composed of corrugated layers the corrugations of which cross oneanother in adjacent layers. At the top and the bottom of the bodystrings or strips 94 are arranged and along the vertical sides stringsor strips 96 for division of the contact body into two groups ofchannels 24 and 30, respectively. The exchanger body is provided with acasing which encloses the vertical sides thereof and has an opening 140near the bottom of one side and an opening 142 near the top at theopposite side for passage of the air to be conditioned through thechannels 30.

In the embodiment according to FIG. 8 the two groups of channels havebeen brought about by means of alternating plane layers 122 andcorrugated layers 124 the corrugations of the latter ones extendingvertically so that the exchanger body is operative according to thecounter-current principle. The cooling air flows through the verticalchannels 24 formed by each second corrugated layer and the plane layersadjacent the same from the top face or upper side of the exchanger bodyvertically downwards. The air to be conditioned is admitted throughlower lateral openings 32 to a distribution interspace 126 and upwardsthrough thechannels 30 to an upper interspace 128 opening towardslateral outlets 36. In order to cover the edges where no flow has totake place, frame elements 130 are disposed at the top and the bottomand vertical frame elements 132 along the channels 30 for the air to beconditioned. The channels 24 for the cooling air are laterally coveredby frame elements 134. The corrugated layers 124 need not bediffusion-tight as they on both sides are in contact with one and thesame fluid. Instead, they may have an intermediate portion of thin metalsheet which has high heat conductivity. This intermediate portion is onboth sides provided with a coating of sorbing agent facing the channelsfor the air to be conditioned and with a water absorbing lining facingthe channels for the cooling air in the same manner as described above.

The embodiment illustrated in FIG. 9 differs from the preceding onesmainly in that the upper interspace 126 and the lower interspace 128have decreasing height in a direction from the inlet openings 32 and theoutlet openings 36, respectively, by the layers 124 being cut offobliquely in a corresponding manner.

DESCRIPTION OF CONDITIONING PLANT The plant shown in FIG. 10 has amoisture exchanger 10 which generally is of the structure shown in'FIG.5. Atmospheric air is sucked in through a fan 144 to the tubular socket14 and flows thereafter in substantially horizontal direction throughthe channels 30 of the exchanger body to an outlet socket 16. Thecooling air is constituted by consumed room air which streams throughthe channel 104 the channels 24 of the exchanger body and the outlet 20to the suction side of a fan 146 which leads the cooling air off to theatmosphere. In this embodiment the heater 52 is gas-fired and has a gassupply conduit 148 with a burner 150 mounted within an outer casing 152..The products of combustion escape through a conduit 154 to the outlet20.

Provided in the outlet socket 16 for the dried and conditioned air is amoistener 156 e.g. of the kind disclosed in the US. Pat. No. 3,262,682and the UK. Pat. No. 1,055,796. Water is caused to circulateintermittently through the moistener 156 by means of a pump 158, asupply pipe 160 and a return pipe 162 which is connected to the suctionside of the pump 158. Water is supplied to the moistener from the mainpipe 148 (159) through a branch pipe 164 controlled by a valve 166. Toprevent the content of salts and the like in the circulating water toreach unsuitable high values, the water content is renewed at regularintervals through a drain pipe 168 controllable by a valve !79.

The moistened and thereby additionally cooled air flows into the room tobe conditioned according to the arrow 172.

EXPLANATION OF INVENTIVE PROGRESS BY PSYCI-IOMETRIC GRAPH In thepsychometric graph shown in FIG. 11 the ordinate represents the absolutewater vapor content of the air in e.g. grams per kilogram air and theabscissa thereof the temperature of the air. In addition the graphrepresent various relative moisture contents of the air. The air to beconditioned is introduced through the fan 144 and has the stateaccording to point 174 which may be a relative moisture content of about45 percent and a temperature of 35 C. In the moisture exchanger 10 thisair is dried to the state 176 which e.g.

is a relative moisture content of percent and a temperature of 22 inwhich state the conditioned air is introduced into the room. Thedifference between the distance of these points from the abscissarepresents 7 the quantity of water removed from the air. In the percentand a temperature of 23 C. When this air is utilized for the cooling inthe drying apparatus 10 it is subjected to a change of stateapproximately according to the graph 182 i.e. it takes up greatquantities of moisture by evaporation of the water absorbed by thewater-absorbing layers 44 and reaches finally a state approximatelyaccording to the point 184 which may correspond to saturated air.

Between the points 174 and 176 the air to be conditioned is subjected toa change of state accordingto the graph 186, Le. the moisture content isreduced and at the same time also the temperature due to the presence ofwater in the channels 24. If, to the. contrary, the drying of the air tobe conditioned had been efiected without the simultaneous cooling of theair, the .change of the condition of this air would have followed thegraph 188 in FIG. 11, ie it had required drying down to relativemoisture content of below 2 percent under simultaneous rise oftemperature above 70 C to reach the same low absolute moisture contentas is present at the point 176. In order then to arrive at the stateaccording to this point a particular cooling must be performed accordingto the line 190 extending in parallel to the abscissa.

According to an other embodiment of the invention the heating fluid forthe regeneration may be constituted by steam which may have atemperatureof 100 C or even more. In theregeneration process acondensation of steam. occurs the. condensate then being sucked up bythe porous layers 44. In some cases water may be supplied tothe layers44 laterally adjacent the zone which at a certain'moment is subjected toregeneration and in which air heatedin advance may be supplied to thechannels for theair to be conditioned in usual manner for expelling themoisture taken up by the drying fluid. The adjacent channels are thensealed off so that no flow of cooling air comes into existence withinthe same.

While one more or less specific embodiment of. the invention has beenshown and described, it is to be an derstood that this is for purpose ofillustration only, and that the invention is not to be limited thereby,but its scope is to be determined by the appended claims:

what is claimed is:

1. Process of drying air comprising passing the air to be conditionedover a heat conductive impermeable partition having a surface coatedwith a desiccant, the opposite side of said partition having a poroussurface, maintaining said opposite porous surface wet with water, andsimultaneously passing another air stream substantially at atmosphericpressures over said waterwet surface, whereby both surfaces areevaporatively cooled by evaporation of the water from said opposite insurface while the air passed over the said first surface is both driedand evaporatively cooled in flowing heat 7 conductive and drying contactwith said desiccant.

2. The method as defined in claim 1 wherein only-isolated portions ofsaid opposite surface are progressively wet witha member-of the groupconsisting of hot water and the steam supplied under heat exchangeconditions to condense at least a portion suflicient to wet said surfaceportion, heating an opposite isolated portion of said first surfacecoated with desiccant to regenerate said desiccant.

3. The. method of claim 2 wherein the isolated portions of said surfacebeing treated havev the evolved water and moisture disposed ofsimultaneously and independently of .the. said evaporative andconditioning air streams.

4. Process of dryingair as defined in claim 1 wherein said desiccant.coated surface is arranged in a first group of channels through whichthe air to be conditionedis passed, the interior surfaces of saidchannel corresponding to saiddesiccant coated surface and said oppositeporous. side. of said desiccant coated surface being divided. into a.second group of channels. alternately arranged in heat conductivecontact with respect to said first group of channels, said other. airstream being passed over the water-wet surfaces of the opposite poroussurfaced channels to effect cooling of the desiccant and airsimultaneously being dried in passage through said first group ofcharmels.

5. The method asdefinedin claim 4 wherein the desiccant on the surfacesin heat conductive contact of the channels is regenerated in a series,one channel at a time, by wetting and heating an opposite surface with amember of the group consisting of hot water and steam, the steam beingunder heat. exchange conditions to condense at least a portion, therebyheating both opposite surface portions to regenerate said desiccantcoating, and then cooling the said wetted opposite surface of 'a channelmember for subsequent evaporative cooling by passage of said other airstream through said channels.

6. The process as claimed in claim 5- wherein the water is supplied tothe first group of channels in liquid state.

7. The process as claimed in claim 5. wherein in that thev water issupplied to the first group of channels in vapor state.

8. The process. as claimed in claim' 5' wherein the supply of heatingfluid is. effected in succession to the individual channels for thecooling agent, the supply of evaporative air at the sametimebeinginterruptedto at least that of the channels which at anydefinite moment receive heating fluid.

9. The method as claimed in claim 8 wherein the supply of heat is alsointerrupted to at least the channel for the cooling agent situatednearestoutside adjacent saidchannel receiving heating fluid.

10. The process as claimed in claim 8, wherein the. air to beconditioned passing through a channel in'the said secondgroup adjacent achannel in the first-mentioned group which'at the definite moment issupplied with heating fluid, is'withdrawn to an outlet.

11. Theprocess as claimed in claim 10, wherein a channel forv the air tobe conditioned which is adjacent a channel for thecooling air, recentlypassed by heating.

fluid and still warm, is wholly sealed off.

12. The process as claimed in claim 5, whereinwater is caused in aclosed circuit to pass through a heating device, at least one channelfor the cooling agent in a regeneration zone movable above the exchangerbody, and a collecting trough located at the lower portion of said body.

13. An apparatus for drying air in a multi-channel system comprising anexchanger body having heat conductive impermeable partition wallssubdividing said body into two groups of channels, every second channelbeing connect to at least one inlet and at least one outlet for air tobe conditioned and every second intermediate channel being connected toat least one inlet and at least one outlet for a cooling agent, thechannels for the air to be conditioned having a coating of a desiccantagent, the opposite channel walls having surfaces only sufficientlyporous to retain water thereon, means for wetting said channel surfaceswith water and means for passing an air stream through said water-wetchannels to cool said water-wet walls by evaporation of the watertogether with the desiccant by heat exchange coated upon the oppositewall surfaces of the alternate channels.

14. The apparatus as claimed in claim 13, wherein the source of water isadapted to deliver the water in liquid state.

15. The apparatus as claimed in claim 13, wherein the source of water isadapted to deliver the water in vapor state.

16. The apparatus as claimed in claim 13, wherein the channels in theexchanger body for the cooling agent are disposed to cooperate withmembers for intermittent supply of water to the individual cooling agentchannels.

17. The apparatus as claimed in claim 16, wherein said members include aspraying device surrounded by a hood and disposed over one side of theexchanger body and located displaceably along said side.

18. The apparatus as claimed in claim 17, wherein the spraying devisewith the surrounding hood is disposed over and displaceable along theupper side of the exchanger body.

19. The apparatus as claimed in claim 17, wherein in a conduit leadingto the spraying device is provided a heater element by means of whichthe heating agent is heated to be utilized thereupon for indirectheating of the sorbing agent in the outer group of channels andregeneration of said agent.

20. The apparatus as claimed in claim 17, wherein in addition to thehood a screen is provided in the path of the air to be conditioned inthe passage leading from said second group of channels in the exchangerbody, said screen being movable synchronously with the hood and thespraying device and adapted to deflect air moistened during theregeneration to a separate outlet.

21. The apparatus as claimed in claim 20, wherein the screen has suchshape that it completely seals ofi the passage through those channelsfor the air to be conditioned which are located adjacent that thosechannels from which regeneration air is withdrawn to said outlet.

22. The apparatus as claimed in claim 17, wherein the hood is shaped tocompletely seal off adjacent channels for cooling agent which areadjacent immediately those channels for air to be conditioned which attheir opposite side are heated by the heating trough is mounted belowthe exchanger body for collecting excess water which is returned by apump to the heating element and the upper side of the exchanger body.

2. The method as defined in claim 1 wherein only isolated portions ofsaid opposite surface are progressively wet with a member of the groupconsisting of hot water and the steam supplied under heat exchangeconditions to condense at least a portion sufficient to wet said surfaceportion, heating an opposite isolated portion of said first surfacecoated with desiccant to regenerate said desiccant.
 3. The method ofclaim 2 wherein the isolated portions of said surface being treated havethe evolved water and moisture disposed of simultaneously andindependently of the said evaporative and conditioning air streams. 4.Process of drying air as defined in claim 1 wherein said desiccantcoated surface is arranged in a first group of channels through whichthe air to be conditioned is passed, the interior surfaces of saidchannel corresponding to said desiccant coated surface and said oppositeporous side of said desiccant coated surface being divided into a secondgroup of channels alternately arranged in heat conductive contact withrespect to said first group of channels, said other air stream beingpassed over the water-wet surfaces of the opposite porous surfacedchannels to effect cooling of the desiccant and air simultaneously beingdried in passage through said first group of channels.
 5. The method asdefined in claim 4 wherein the desiccant on the surfaces in heatconductive contact of the channels is regenerated in a series, onechannel at a time, by wetting and heating an opposite surface with amember of the group consisting of hot water and steam, the steam beingunder heat exchange conditions to condense at least a portion, therebyheating both opposite surface portions to regenerate said desiccantcoating, and then cooling the said wetted opposite surface of a channelmember for subsequent evaporative cooling by passage of said other airstream through said channels.
 6. The process as claimed in claim 5wherein the water is supplied to the first group of channels in liquidstate.
 7. The process as claimed in claim 5 wherein in that the water issupplied to the first group of channels in vapor state.
 8. The processas claimed in claim 5 wherein the supply of heating fluid is effected insuccession to the individual channels for the cooling agent, the supplyof evaporative air at the same time being interrupted to at least thatof the channels which at any definite moment receive heating fluid. 9.The method as claimed in claim 8 wherein the supply of heat is alsointerrupted to at least the channel for the cooling agent situatednearest outside adjacent said channel receiving heating fluid.
 10. Theprocess as claimed in claim 8, wherein the air to be conditioned passingthrough a channel in the said second group adjacent a channel in thefirst-mentioned group which at the definite moment is supplied withheating fluid, is withdrawn to an outlet.
 11. The process as claimed inclaim 10, wherein a channel for the air to be conditioned which isadjacent a channel for the cooling air, recently passed by heating fluidand still warm, is wholly sealed off.
 12. The process as claimed inclaim 5, wherein water is caused in a closed circuit to pass through aheating device, at least one channel for the cooling agent in aregeneration zone movable above the exchanger body, and a collectingtrough located at the lower portion of said body.
 13. An apparatus fordrying air in a multi-channel system comprising an exchanger body havingheat conductive impermeable partition walls subdividing said body intotwo groups of channels, every second channel being connect to at leastone inlet and at least one outlet for air to be conditioned and everysecond intermediate channel being connected to at least one inlet and atleast one outlet for a cooling agent, the channels for the air to beconditioned having a coating of a desiccant agent, the opposite channelwalls having surfaces only sufficiently porous to retain water thereon,means for wetting said channel surfaces with water and means for passingan air stream through said water-wet channels to cool said water-wetwalls by evaporation of the water together with the desiccant by heatexchange coated upon the opposite wall surfaces of the alternatechannels.
 14. The apparatus as claimed in claim 13, wherein the sourceof water is adapted to deliver the water in liquid state.
 15. Theapparatus as claimed in claim 13, wherein the source of water is adaptedto deliver the water in vapor state.
 16. The apparatus as claimed inclaim 13, wherein the channels in the exchanger body for the coolingagent are disposed to cooperate with members for intermittent supply ofwater to the individual cooling agent channels.
 17. The apparatus asclaimed in claim 16, wherein said members include a spraying devicesurrounded by a hood and disposed over one side of the exchanger bodyand located displaceably along said side.
 18. The apparatus as claimedin claim 17, wherein the spraying devise with the surrounding hood isdisposed over and displaceable along the upper side of the exchangerbody.
 19. The apparatus as claimed in claim 17, wherein in a conduitleading to the spraying device is provided a heater element by means ofwhich the heating agent is heated to be utilized thereupon for indirectheating of the sorbing agent in the outer group of channels andregeneration of said agent.
 20. The apparatus as claimed in claim 17,wherein in addition to the hood a screen is provided in the path of theair to be conditioned in the passage leading from said second group ofchannels in the exchanger body, said screen being movable synchronouslywith the hood and the spraying device and adapted to deflect airmoistened during the regeneration to a separate outlet.
 21. Theapparatus as claimed in claim 20, wherein the screen has such shape thatit completely seals off the passage through those channels for the airto be conditioned which are located adjacent that those channels fromwhich regeneration air is withdrawn to said outlet.
 22. The apparatus asclaimed in claim 17, wherein the hood is shaped to completely seal offadjacent channels for cooling agent which are adjacent immediately thosechannels for air to be conditioned which at their opposite side areheated by the heating fluid.
 23. The apparatus as claimed in claim 13,wherein the partition walls of the exchanger body are formed with alining substantially impermeable to water in liquid state or steamstate.
 24. The apparatus as claimed in claim 23, wherein both sides ofsaid lining are porous layers serving as carried for the desiccant agentor as accumulators for the supplied water.
 25. The apparatus as claimedin claim 19, wherein a trough is mounted below the exchanger body forcollecting excess water which is returned by a pump to the heatingelement and the upper side of the exchanger body.